The need to prolong shelf-life of food products, in particularly fresh produce, without harming quality, is well recognized. Many coating formulations are disclosed in the literature.
One of the known methods for coating fresh produce such as onions and edible fungi is to form a coating by applying to the exterior surface of an onion or fungi a gelation solution comprising a hydrocolloid, such as sodium alginate and cross linking the hydrocolloid on the surface by a solution comprising a gelation inducing agent, such as CaCl.sub.2.
The so obtained coating is both biodegradable and edible and provides a protective coating to the treated vegetable. U.S. Pat. No. 3,865,962 discloses a process for coating raw onion products by immersion of the onion in an aqueous dispersion containing water soluble algin and subsequently treating the coated onion with an aqueous calcium ion to induce gelation.
EP 277 448 discloses an edible coating containing gelatin and polysaccaride. A cross-linking agent containing calcium ions is used for obtaining the coating.
However, none of the prior arts disclose a coating containing in its matrix a compound having a specific reference to the surface of the product to be coated.